go语言method 求解

// f2函数的输出看不明白, &argError{arg, "can't work with it"}会自动调用argError 的Error 方法么,求解答

type argError struct {
    arg  int
    prob string
}

func (e *argError) Error() string {
    return fmt.Sprintf("%d - %s", e.arg, e.prob)
}
func f2(arg int) (int, error) {
    if arg == 42 {
        return -1, &argError{arg, "can't work with it"}
    }
    return arg + 3, nil
}

func main() {
    for _, i := range []int{7, 42} {
        if r, e := f2(i); e != nil {
            fmt.Println("f1 failed:", e)
        } else {
            fmt.Println("f1 worked:", r)
        }
    }
}